The present invention relates to carpeting cutters, and more particularly to carpeting cutters which simultaneously cut two different carpets for creating matched abutting edges for joining the two carpets in a seam using conventional seaming techniques.
It is often necessary, when carpeting a large area, such as a wide floor, with wall-to-wall carpeting, to seam together two or more widths of carpeting in order to cover the entire area. This is because carpeting is manufactured and sold in standard widths that are often smaller than the areas which are to be carpeted. Carpeting is often installed over a cushioning material, although it need not be. In a stretched carpet installation, once the cushion has been installed, the carpeting is rough fitted and trimmed, the seams between the carpet are created by cutting the adjoining carpet pieces to create clean edges for seaming and moving the two carpeting pieces as necessary to closely abut the clean edges, and joining the closely abutting edges of carpeting together using a hot-melt carpet seaming tape. The seamed carpet is then stretched to the periphery of the area to be carpeted, the carpet edges are trimmed and fastened to a tack strip or similar device installed along the periphery to provide a neat appearance. In a glue-down installation, the carpeting is rough fitted, and the seams between the carpet are created by cutting the edge of each adjoining piece of carpet to create clean, matched edges for seaming and moving the adjoining carpet pieces as necessary to closely abut the freshly cut edges, and joining the edges either with a carpet seaming tape or by directly gluing the edges to the cushion or the surface to be carpeted if no cushion is used. The rest of the carpet is also adhesively attached to the cushion or surface to be carpeted, and the edges are trimmed and secured to the periphery of the area and covered to provide a neat appearance, using a tack or tackless strip, cove base strip or similar product.
Because it is desirable to make the seams between the pieces of carpeting as invisible as possible, it is necessary that the edges of the carpeting to be joined be trimmed to provide a clean surface for seaming, and be closely matched to each other, to prevent any overlapping or gaps between the two pieces, which would produce visible defects at the seam. Thus, the edges to be abutted are often cut to match one another.
Heretofore, it has been difficult to easily obtain perfectly matching cuts between the two pieces of carpeting to be abutted and seamed. Simply laying a straight edge along the top of the carpeting and cutting downward with a blade through the carpeting pile and backing has produced unsatisfactory results. When carpeting is cut from above--that is, from the pile side--tufts of pile fibers will inevitably be snagged and cut as they are trapped between the backing and the blade. These missing fibers will make the seam visible. The effect is the same as if one took a small scissors and cut some of the pile along a line. It will be clearly visible.
One method for avoiding this difficulty is by using a guide rail for cutting in a relatively straight line from the top of carpeting through the backing between the pile fibers. For example, in U.S. Pat. No. 3,621,573 to Summers a guide rail rests on the top surface of the carpet backing between the pile fibers, and a blade aligned with the guide rail extends downward to cut through the carpeting as the guide rail moves over it. In Canadian patent 907,305, a rug cutting tool which has two parallel guides on either side of the tool body includes a blade disposed between the two plates for cutting down through the carpet. The guide rails of these two inventions are intended to prevent wavering of the knife and erratic cutting. However, care is required when a long cut made with these tools, and the cut made will still have appreciable error. Nor can these tools accurately cut overlapped carpets. An overlapping piece of carpet will force the carpet pile of the underlying pieces down, preventing a user cutting from above to avoid snagging and unevenly cutting the pile on the underlying piece of carpet.
U.S. Pat. No. 4,833,956 to Roberts discloses a cutter for simultaneously cutting overlapped pieces of carpets from one side of the carpet to the other. The Roberts cutter includes two large stacked slots that extend horizontally from the cutter body, so that each slot is bounded above and below by horizontal surfaces open at the front and along the sides. One slot runs parallel to and directly above the bottom plane surface of the body, and the other slot is directly above the first one (and similar in shape), and a blade runs vertically through the middle of both slots at the rear of the body. Thus, when one carpet edge is lifted and inserted into the lower slot and an overlapping carpet edge is inserted into the upper slot, and the cutter body is pushed forward, the carpet edges are directed against the knife edges within, producing a generally aligned cut through the backing and pile of both pieces. However, since the Roberts cutter lifts the carpet edges up off the floor, the cut edges will tend to overlap slightly and may not abut when the cut carpet is lowered onto the floor, and the resulting seam may tend to buckle unless the carpets are pulled apart after cutting. Difficulties can also be expected because, after cutting, the stiff carpeting must part enough to pass around the body at the rear of the Roberts cutter. As the freshly cut edges leave the knife and encounter the body, they must deflect to either side of the body. This deflection can increase the difficulty of use, will also tend to throw off the cut, and fatigue the user, causing error.
All of these tools are disadvantageous because, even if the tools can be used to make two separate cuts simultaneously, the carpeting must still be manipulated thereafter to make the two pieces, and such movement of the carpeting will affect the registration of any simultaneously produced cuts, making a perfect match difficult. Also, because the cuts are being made from the top or edge of the carpet, carpet pile fibers will be snagged or cut. Even where guide rails are used, because the location and arrangement of the carpet pile fibers varies from one manufacturer to another, it may be difficult to avoid cutting carpet pile fibers, and thus gaps or overlapping areas may be produced which will be evident when two abutting edges are joined.
Another solution, is to cut the carpeting from the backing side. This is clearly a better way to produce the edges to be mated because if the backing alone is cut, the pile fibers will not be snagged and cut. However, when an operator turns the edge to be cut, and pins it (using his body weight) between the surface to be carpeted and a straight edge, he compresses the pile. Because operators cannot control the depth of their cut with any precision, they often snag and cut the compressed and skewed underlying pile, again creating an unsightly, visible area after seaming.
As shown in my U.S. patent application, Ser. No. 07/767,325 filed Sep. 30, 1991, now U.S. Pat. No. 5,159,758, the carpet backing of two abutting pieces of carpeting can be cut simultaneously from the back side while the carpeting is in its normal position with the carpet pile facing up. While the use of this tool avoids completely the problem of cutting and snagging carpet fibers, as occurs when carpet is cut from above or from the edge, a gap between the two pieces of carpeting is produced which must be closed by moving the carpets to abut the edges. As noted above, this subsequent movement of the carpeting may throw off the registration of the cut edges, and the edges may, thereafter, not be perfectly aligned for seaming.
Accordingly, the need exists for an apparatus for cutting two carpet edges to produce nearly perfectly abutting edges, without further movement of the carpeting, and without cutting, snagging or otherwise removing carpet pile fibers along the edge to be joined, so as to produce a nearly invisible seam after the two abutting edges are joined using conventional methods.